Refrigerator having a heat dissipating device for the electric motor thereof



9 1948- J. J. BAUMAN fi fi REFRIGERATOR HAVING A HEAT DISSIPATING' DEVICE FOR THE ELECTRIC MOTOR THEREOF Filed June 30, 1944 Patented Oct. 19, 1948 REFRIGERATOR HAVING A HEAT DISSIPAT- ING DEVICE FOR THE ELECTRIC MOTOR THEREOF John J. Bauman, Abington, Pa., assignor, by -mesne assignments, to Philco Corporation, Philadelphia, Pa., a corporation of Pennsyl- Application June so. 1944, Serial No. 542,889 8 Claims. (01. 62-1) The invention disclosed in the co-pending application of Malcolm G. Shoemaker, Serial Number 528,521, filed March 29, 1944, now abandoned, contemplates the use of a motor operated blower to circulate air through the main food storage compartment of a refrigerator, said motor being located within the insulation between the inner liner and outer shell of the cabinet and being supported on the liner in heat conducting relation therewith.

It is desirable with this arrangement that no 'direct contact shall exist between the motor and the outer shell, since such contact would afford a direct path for transfer of heat from external sources to the interior of the cabinet. Such contact would be undesirable also because of a tendency of the extended outer shell to amplify the vibration and noise of the motor. It has been found that under certain conditions, in the event for example that the motor becomes heated excessively, that it is advantageous to have a direct heat conducting path between the motor and outer shell of the refrigerator, so that the excessive heat may be conducted from the motor to the shell for dissipation to the atmosphere,

Again, in motor-compressor units of the type now conventionally used in domestic and other refrigerators, the motor and pump are resiliently mounted within a hermetically sealed shell and free from rigid contact therewith. The compressor motor may be subject to overheating for various known reasons unnecessary to describe, and if such conditions should arise it would be beneficial to have a direct path for heat conduction from the motor to the shell, for the same reason as stated above in connection with the blower motor.

With the aforesaid examples in mind, it is an object of the present invention to provide means operative only under predetermined temperature conditions for establishing an efficient heat conducting path between elements normally lacking such path.

Another object is to provide a device for conductively connecting a first member subject to overheating with a second member of a character to dissipate said heat, whereby such connection is made automatically in accordance with the temperature of said first member so as to maintain a substantially constant normal temperasaid conductive connection in a simplified, efficient and economical manner.

It is a still further object of the invention to provide means, operating in conjunction with the aforesaid connecting means, for signalling the overheated condition of said first member.

More specifically, it is an object of the invention to provide novel means for maintaining a motor at a substantially constant temperature under conditions of motor-load fluctuation.

In the attached drawings;

Figure 1 is a vertical sectional view of a portion of a refrigerator embodying the invention;

Figure 2 is an enlarged sectional view showing details of an element of the refrigerator;

Figure 3 is a view taken along the line 33 of Figure 2;

Figure 4 is a sectional view of a motor-compressor unit embodying the invention, and

Figure 5 is a fragmentary sectional view of a motor-compressor unit illustrating a modification within the scope of the invention.

Figure 1 shows a portion of a household refrigerator of the type described and claimed in the aforementioned co-pending application of Malcolm G. Shoemaker. In this refrigerator the food storage space is divided into upper and lower compartments, the lower compartment containing a freezing unit cooled by a primary evaporator system, and the upper compartment providing a moist cold food-storage space, cooled by a secondary evaporator of the type in which the coils are wrapped around the inner liner in intimate heat exchange relation therewith.

A particular feature of the refrigerator of the aforesaid application is the forced circulation of air through the upper compartment and into heat exchange relation with a portion of the primary evaporator to remove excess humidity. This circulation is accomplished by providing an air channel having its outlet into the food storage compartment at a position adjacent the top of the latter, and its inlet at a position adjacent the bottom of the compartment. From the inlet opening a channel extends adjacent the primary evaporator and upwardly at the back of the liner to the outlet aperture.

01 especial interest to the instant invention is the provision in the air channel of a motor-actuated blower for causing said circulation. The

operation of the blower is preferably responsive to excessive humidity within the food-storage compartment, 1. e., when the humidity within the compartment reaches the dew point it is desir able to remove a portion of it to prevent conaesneoa densate forg on the walls of the compartment. When such condition arises, a humidostat, or some other adequate humidity responsive means, causes the motor to start the blower circulating the air through the channel and into contact with the primary evaporator upon which the excess moisture condenses and flows out into a collecting receptacle. The above operation is more specifically described in the aforesaid copending application, and as the structure and operation form no part, per se, of this invention, further description thereof is considered unnecessary.

With respect to the present invention, it is to be noted that the blower motor is located within the insulation surrounding the said compartments, and as illustrated in the drawings here- 'with is supported by the inner liner structure without direct connection with the outer shell. reason of this construction, there is no direct heat conducting path through which the high room temperature may be conducted into the refrigerator to put additional load upon the refrigeration apparatus, The motor may become overheated, however, due for example to excessively long operating periods, and at such times it is advantageous and desirable to provide some means for dissipating the excess heat.

d tubing it, secured in convoluted arrangement to the exterior surface of that part of the liner which forms the compartment i, said tubing constituting the evaporator of the secondary refrig= erant circuit. Condensation of the secondary liquid is efiected by means of heat exchange association between the secondary tubing and a small evaporator (not shown) which constitutes a series connected portion of the main primary circuit associated with the freezing compartment 5%.

. 5 is accomplished through the medium of the The present invention provides a device ,re- I sponsive to such excessive temperature condition for establishing a heat conducting path from the motor to the outer shell by way of which the excess heat may be conducted to the shell for radiation to the ambient atmosphere.

Referring now more particularly to the drawings, the refrigerator of which a fragmentary portion i is shown in Figure 1, comprises an outer casing or shell 3. and an inner shell or liner member 4, said liner enclosing the food storage space, indicated generally at 5, which is divided by a double thickness insulating shelf 6 into a main upper food storage compartment I and a lower freezing compartment 8. The compartment 1 may be fitted with one or more shelves 9 of any desired type. Vertical and horizontal breaker strips in and II, respectively, of low thermal conductivity, are fitted around the lower marginal edge of the front access opening l2, while thermal insulation, portions of which are indicated at i3, completely surround the inner liner member 4. The cabinet is provided with a door l4, said door being adapted to seat in the plane of-the breaker strips in and H, as illustrated in Figure 1.

A machinery compartment I5 is located in the lower part of the cabinet structure, which compartment houses the compressor unit indicated generally at I6. The primary evaporator, shown at H, may be supported within the refrigerator in any convenient manner, as for example, by welding its coils to the outside walls of the freezing compartment 8. The partition shelf 6 being interposed between the primary evaporator section or freezing compartment and the main storage compartment 1 makes it possible to operate said compartment I at relatively high temperatures as compared with the temperature of the evaporator l1 and to prevent the undesired frosting out of moisture present in said compartment I. As

secondary tubing i9, while additional transfer capacity is provided and the tion of undesirable humidity from said compartment is accomplished by effecting periodic circulation of compartment air through the several air ducts 25 appearing in Figure 1, and thence, into the lower passage 26 of said ducts which passage is in heatexchange relation with the primary evaporator tubing 2?. This circulation is effected, as and when required, by means of a motor 38 and associated fan 35 operable periodically in response to the humidity conditions existing in compartment 5.

In accordance with the instant invention, and as more clearly illustrated in Figure 2, the motor at is located within the insulation in a position which places the rear portion 32 of said motor in proximity to the outer shell 3. The motor is provided with a pair of spaced thermally responsive members 33 attached to the motor wall as by screws 36 which serve. also to secure the stator 35 of the motor to the shell or housing 35 thereof. The members 33 are preferably bi-metallic, and each comprises a flat elongate base portion 36 having its ends inturned toward each other as to form fingerportions 37 which are substantally parallel with said base portion and the rear wall of outer shell 3. These bi-metal members may be formed in any well-known manner, of

metals, such as brass and monel, having different coefficients of expansion so that heat from the motor in excess of a predetermined amount will cause the finger portions-to move outwardly to contact the outer shell 3 of the refrigerator so as to form a direct heat-conducting path between the motor and the shell. Such contact permits excess heat to be conducted through the members to the shell, from which it is radiated into the ambient atmosphere.

In order to eliminate undesired conduction of heat through the motor, during periods when the members 311 are not in contact with the shell 3, the casing 36 of said motor may be made of a low heat-conducting material, such as molded plastic. During operating periods the motor heat is conducted through the stator bolts to the bimetal elements 33, whichwill be moved into contact with the shell if the heat becomes excessive.

Figure 4 illustrates the essentials of a her= metically sealed motor-compressor unit of hown type. Generally, the unit comprises a motor 5Q reasons aforesaid. The present invention pro-- vides a means for connecting the motor to the shell in the following manner.

Attached to the stator 45 o be motor are a plurality of bi-metal elements 46 similar in construction to those described above in connection with the blower motor. The elongate base portion 36a of each is suitably secured to the stator in a manner such that finger portions 31a are disposed adjacent and substantially parallel to the shell. If for some reason the motor should become overheated, these fingers, responsive to such overheating, move outwardly into intimate heat transfer contact with the shell to form a path for conduction of the excess heat to the shell which, in turn, will radiate the heat to the ambient atmosphere.

In the modification shown in Fig. 5, a conductor member 47 is provided which is separate from the thermo sensitive or bi-metallic actuator 48 so that the latter is relieved of the function of conducting heat. The conductor is extended and retracted by action of the member 48 in obvious manner and the principle of operation remains unchanged.

In the embodiments illustrated and described, conditions tending toward overheating are adequately taken care of by the direct heat-conducting path established when the motor heat rises above a predetermined value. However, the invention is also applicable to installations in which the establishment of such path will occur only when overheating has become critical and, as a consequence, the apparatus should be shut down for inspection and possible repair. It will be evident also that the principle of the thermally responsive conductive connection may be employed for compensating conditions tending toward too great reduction of temperature in a given member or mechanism, in which case the conductive connection would be maintainednormally and would be broken if the temperature of the member or mechanism was reduced below the predetermined minimum. In certain instances, the heat dissipating element may be utilized as a radiator of sound, and the establish-.

the other of said elements for relief of said condition. It will be evident also the principle involved may find useful applications other than those herein set forth for purpose of illustration without departing from the invention as defined in the appended claims.

I claim:

1. The combination with a refrigerator includin an outer shell, an inner liner thermally sepas rated from said shell by suitable insulation, an air circulating blower, and a motor for operating said blower, said motor being supported independently of said outer shell but in proximity thereto; of a heat conductive member attached to said motor in, heat exchange relation therewith, said member being movable in response to heat in said motor into contact with said outer shell thereby to form a path for conduction of heat to said shell.

2. The combination with a refrigerator including an outer shell, an inner liner spaced from said shell, insulation interposed between said shell and liner, an air circulating blower, and a motor for operating said blower supported independently of said outer shellbut in proximity thereto; oi! a heat conductive member attached to said motor in heat exchange relation therewith and movable in responsive to heat in said motor in excess of a predetermined amount into contact with said outer shell to thereby afford a path for conduction of said excessive heat to said shell,

3. The combination with a refrigerator including an outer shell, an inner liner spaced from said shell, insulation interposed between said shell and liner, an air circulating blower, and a motor for operating said blower, said motor being supported independently of said outer shell but in proximity thereto; of a bi-metal heat conductive member attached to said motor in heat exchange relation therewith, said member being movable in response to heat in said motor in excess of a predetermined amount into contact with said outer shell to thereby afford a path for conduction of said excessive heat to said shell.

4. The combination with a motor compressor unit including motor-actuated pumping means mounted within and substantially free from contact with a housing; of a heat conductive member attached to said means in heat exchange relation therewith, said member being movable in response to heat in said means into contact with said housing to thereby afford a path for conduction of said heat to said housing.

5. The combination with a motor-compressor unit including motor-actuated pumping means mounted within a hermetically sealed shell and substantially free from contact with the latter; of a plurality of heat conductive members attached to said means in heat exchange relation therewith, said members being movable in response to excessive heat in said means into contact with said shell to thereby provide a path for conduction of said excessive heat to said shell.

6. The combination with a motor-compressor unit including motor-actuated pumping means mounted Within a hermetically sealed shell and substantially free from contact with the latter; of, a plurality of bi-metal heat conductive members attached to said means in heat exchange relation therewith, said members being movable in response to excessive heat in said means into contact with said shell to thereby provide a path for conduction of said excessive heat to said shell to reduce the temperature of said means.

'7. The combination with a motor subject to overheating and a heat dissipating housing for said motor normally thermally separated therefrom, of a heat conductive member in heat con ductive relation with said motor and adapted to move into contact with said housing in response to a predetermined heatcondition. in said motor t f-M ENCES orrm to thereby establish a path for the conductionof heat from said motor to said housing. g g ggig ggf gf are of record m the 8. The combination with a-motor subject to V overheating and a heat dissipating housing for 5 STATES PATENTS said motor normally thermally separated there- Number e a Date from, of oi-metallic means in heat conductive re- 1 705 7 Rnwan Man 19 1929 iation with said motor and adapted to move into 2333.025 Wolf May 1942 contact with said housing in response to a pre-. 2,363,375 w mm 1944 determined heat condition in said motor to thereit by establish a path for the conduction of heat from said motor to said housing.

' JOHNJ.BA.

Qeificate of ifiorrection Patent No. 2,451,903. 7 October 19, 1948.

JOHN J. BAUMAN It is hereby certified that errors appear in the printed specification of the above numbered patent requiring correction as follows:

Column 1, line 3, for the serial number 528,521 read 528,581; same line strike out the word abandoned and insert instead Patent Number 2,416,854, dated February 47 w and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case in the Patent ce.

Signed and sealed this 8th day of March, A. D. 19%9.

F. nn; Assistant Uommz'eez'oner oi 1 r: 

